High Inhibition for a Co^II Tetrazole Bi-pyrazole Dinuclear Complex against Fusarium Oxysporum f. sp. Albedinis

New coordination compounds made of two novel tetrazole and C,N-bipyrazole ligands, 2-(3,5,5′-trimethyl-1′H-[1,3′-bipyrazol]-1′-yl)acetonitrile (L1), and 1′-((1H-tetrazol-5-yl)methyl)-3,5,5′-trimethyl-1′H-1,3′-bipyrazole (HL2), were prepared and fully characterized by spectroscopic techniques. Their crystal structures were identified by single-crystal X-ray diffraction revealing mononuclear complexes: [Ni(L1)₃](ClO₄)₂ (1), [Cd(L1)₂Cl₂] (2), [Cu(HL2)(L2)]ClO₄ (3), [Cu(L2)₂] (4) and a dinuclear complex [Co₂(HL2)(L2)Cl₃] (5) comprising Co^II ions in octahedral and tetrahedral surrounding within the same unit. Noticeably, 3 and 4 show different architectural structures due to ligand deprotonation as well as the effect of the counter anion. All compounds demonstrated antimicrobial activity against Gram (+) bacteria Listeria innocua and Staphylococcus aureus, as well as Gram (−) bacteria such as Escherichia coli and Pseudomonas aeruginosa, and antifungal activity against pathogenic fungi Geotrichum candidum, Aspergillus niger, and Penicillium crustosum. Interestingly, a high inhibition activity of 97 % was reached for 5 with a low concentration of only 81.1 μmol/L against Fusarium oxysporum f. sp. Albedinis, which is commonly damaging palm trees crops.